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<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
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    <script type="text/javascript">
        function getArea(r){
            return Math.PI*r*r;
        }
        console.log("半径5cm的圆的面积是"+getArea(5)+"平方厘米")
    </script>
</body>
</html>